The long-range objectives of proposed work is to advance the treatment of small-cell carcinoma of the lung by studying the ecotopic production of human neurophysins, of various hormones, and of hormone-related peptides, by these tumors. Specific RIAs for human neurophysins (HNPs) neurohypophysial peptides (VP, OT, VT) and CLIP (18-39 ACTH) will be used to monitor and improve therapy of patients with small cell carcinoma. In such patients, the plasma and urine concentration of one or more of these substances should provide an effective means of indexing residual tumor mass and thereby of monitoring and directing therapy. The production (biosynthesis, storage, and release) of the neurohypophysial principles by tumor cells is also being studied, and this compared with normal production by neurons of the hypothalamus. Knowledge gained in these studies should lead us to a better understanding of the pathophysiology of small cell carcinoma and possibly to a more rational approach to therapy.